IL-5 levels in the serum and blister fluid of patients with bullous pemphigoid: correlations with eosinophil cationic protein, RANTES, IgE and disease severity

Eosinophils in Oral Disease: A Narrative Review

The prevalence of diseases characterised by eosinophilia is on the rise, emphasising the importance of understanding the role of eosinophils in these conditions. Eosinophils are a subset of granulocytes that contribute to the body's defence against bacterial, viral, and parasitic infections, but they are also implicated in haemostatic processes, including immunoregulation and allergic reactions. They contain cytoplasmic granules which can be selectively mobilised and secrete specific proteins, including chemokines, cytokines, enzymes, extracellular matrix, and growth factors. There are multiple biological and emerging functions of these specialised immune cells, including cancer surveillance, tissue remodelling and development. Several oral diseases, including oral cancer, are associated with either tissue or blood eosinophilia; however, their exact mechanism of action in the pathogenesis of these diseases remains unclear. This review presents a comprehensive synopsis of the most recent literature for both clinicians and scientists in relation to eosinophils and oral diseases and reveals a significant knowledge gap in this area of research.

Advancements in Bullous Pemphigoid Treatment: A Comprehensive Pipeline Update

ABASTRACT

Bullous pemphigoid (BP) is a common autoimmune bullous disease affecting mainly the elderly, with rising incidence due to increased life expectancy. This disease is characterized by tense bullous lesions on normal or erythematous skin, accompanied by pruritus. BP pathogenesis involves autoantibodies against hemidesmosomal proteins BP180 and BP230, leading to detachment at the dermo-epidermal junction as well as blister formation. BP is associated with coexisting comorbidities and drug exposure, and its management often requires high doses or chronic use of systemic glucocorticoids, posing risks of adverse effects. This review focuses on novel treatment options for BP, exploring therapies targeting different immune pathways. Rituximab, a CD20 monoclonal antibody, depletes B-lymphocytes and has shown efficacy in severe cases. Dupilumab, targeting interleukin (IL)-4 receptor α and thus blocking IL-4 and IL-13, downregulates type 2 helper (Th2) responses and has demonstrated promising results. Targeting eosinophil-related molecules using bertilimumab and AKST4290 has yielded positive results in clinical trials. Omalizumab, an immunoglobulin (Ig) E antibody, can reduce disease severity and allows corticosteroid tapering in a number of cases. Complement inhibitors such as nomacopan and avdoralimab are being investigated. IL-17 and IL-23 inhibitors such as secukinumab and tildrakizumab have shown potential in a limited number of case reports. Neonatal Fc receptor antagonists such as efgartigimod are under investigation. Additionally, topical therapies and Janus kinase inhibitors are being explored as potential treatments for BP. These novel therapies offer promising alternatives for managing BP, with potential to improve outcomes and reduce high cumulative doses of systemic corticosteroids and related toxicities. Further research, including controlled clinical trials, is needed to establish their efficacy, safety, and optimal dosing regimens for BP management.

Advancing Treatment in Bullous Pemphigoid: A Comprehensive Review of Novel Therapeutic Targets and Approaches

Bullous pemphigoid is one of the most common autoimmune bullous diseases occurring primarily in the elderly. Pathogenic autoantibodies against BP180 and BP230 at the dermal-epidermal junction cause subepidermal blisters, erosions, and intense pruritus, all of which adversely affect the patients' quality of life and may increase their morbidity and mortality. Current systemic treatment options for bullous pemphigoid are limited to corticosteroids and immunosuppressants, which can have substantial side effects on these vulnerable patients that even exceed their therapeutic benefits. Therefore, more precisely, targeting therapies to the pathogenic cells and molecules in bullous pemphigoid is an urgent issue. In this review, we describe the pathophysiology of bullous pemphigoid, focusing on autoantibodies, complements, eosinophils, neutrophils, proteases, and the T helper 2 and 17 axes since they are crucial in promoting proinflammatory environments. We also highlight the emerging therapeutic targets for bullous pemphigoid and their latest discoveries in clinical trials or experimental studies. Further well-designed studies are required to establish the efficacy and safety of these prospective therapeutic options.

Targeting type 2 inflammation in bullous pemphigoid: current and emerging therapeutic approaches

Bullous pemphigoid (BP) is one of the most common autoimmune bullous diseases and mainly affects an elderly population with multi-morbidity. Due to the frailty of many BP patients, existing treatment options are limited. The blisters associated with BP result from IgG and IgE autoantibodies binding to the central components of hemidesmosome, BP180, and BP230, stimulating a destructive inflammatory process. The known characteristic features of BP, such as intense pruritus, urticarial prodrome, peripheral eosinophilia, elevated IgE, as well as recent expanding evidence from in vitro and in vivo studies implicate type 2 inflammation as an important driver of BP pathogenesis. Type 2 inflammation is an inflammatory pathway involving a subset of CD4+ T cells that secrete IL-4, IL-5, and IL-13, IgE-secreting B cells, and granulocytes, such as eosinophils, mast cells, and basophils. It is believed that effectors in type 2 inflammation may serve as novel and effective treatment targets for BP. This review focuses on recent understandings of BP pathogenesis with a particular emphasis on the role of type 2 inflammation. We summarize current clinical evidence of using rituximab (B-cell depletion), omalizumab (anti-IgE antibody), and dupilumab (anti-IL-4/13 antibody) in the treatment of BP. The latest advances in emerging targeted therapeutic approaches for BP treatment are also discussed.

Refractory Bullous Pemphigoid Successfully Treated with Reslizumab: A Possible Novel Therapeutic Modality

Bullous pemphigoid (BP) is a chronic, autoimmune blistering disease that has concerning morbidity and mortality rates. Recently, several studies have focused on eosinophils due to their significant role in the pathogenesis of BP, considering that they are ubiquitous in the serum, tissue, and blister fluids of patients with BP. With this context, precision therapy that targets mediators of eosinophil activity could be a possible novel therapeutic strategy. Interleukin (IL)-5 is crucial for B-cell maturation, which consequently results in immunoglobulin production, and promotes eosinophil differentiation, proliferation, and activation. To our best knowledge, reslizumab has not yet been reported to treat BP. Herein, we report a case of steroid- and omalizumab-resistant BP treated successfully using reslizumab. Our data suggest that IL-5 could be a novel specific biologic target within the entire immunopathogenesis of BP, and reslizumab would be a novel therapeutic modality.

Bullous pemphigoid: The role of type 2 inflammation in its pathogenesis and the prospect of targeted therapy

Bullous pemphigoid (BP) is an autoimmune disease that mainly occurs in the elderly, severely affecting their health and life quality. Traditional therapy for BP is mainly based on the systemic use of corticosteroids, but long-term use of corticosteroids results in a series of side effects. Type 2 inflammation is an immune response largely mediated by group 2 innate lymphoid cells, type 2 T helper cells, eosinophils, and inflammatory cytokines, such as interleukin (IL)-4, IL-5 and IL-13. Among patients with BP, the levels of immunoglobulin E and eosinophils are significantly increased in the peripheral blood and skin lesions, suggesting that the pathogenesis is tightly related to type 2 inflammation. To date, various targeted drugs have been developed to treat type 2 inflammatory diseases. In this review, we summarize the general process of type 2 inflammation, its role in the pathogenesis of BP and potential therapeutic targets and medications related to type 2 inflammation. The content of this review may contribute to the development of more effective drugs with fewer side effects for the treatment of BP.

Dipeptidyl Peptidase 4 Inhibitor‒Associated Bullous Pemphigoid Is Characterized by an Altered Expression of Cytokines in the Skin

Dipeptidyl peptidase 4 inhibitors (DPP4is), commonly used drugs for treatment of type 2 diabetes, increase the risk for bullous pemphigoid (BP). Currently, the mechanism leading to the loss of immunological tolerance of the cutaneous adhesion molecule BP180 as well as similarities and differences in disease progression between DPP4i-associated BP (DPP4i-BP) and DPP4i-independent regular BP are largely unknown. We analyzed the expression of 32 cytokines and two proteases by Luminex and ELISA assays in samples taken from lesional and nonlesional skin of patients with regular BP or DPP4i-BP and healthy controls. Cytokines mediating B-cell survival and targeting such as BAFF, CCL4, CXCL12, and IL-6 were expressed at a higher level in the lesional regular BP skin than the levels in the lesional DPP4i-BP skin. The DPP4i-BP samples had increased levels of eosinophilic cytokines CCL1, CCL17, CCL26, and IL-5, which correlated with the serum level of anti-BP180 NC16A IgG autoantibodies. The mRNA expression of BAFF, IL6, CCL1, CCL17, CCL26, and IL5 measured by qPCR correlated with the protein levels. Taken together, the cutaneous cytokine profiles were found to provide distinctive molecular fingerprints between regular BP and DPP4i-BP.

A Review of the Immunologic Pathways Involved in Bullous Pemphigoid and Novel Therapeutic Targets

Bullous pemphigoid (BP) is a rare, chronic antibody-mediated autoimmune blistering disease primarily affecting the elderly, with an age of onset over 60. Current treatment options are limited and involve the use of corticosteroids and immunosuppressants, but their long-term use is associated with significant morbidity and mortality. In Japan, human intravenous immunoglobin is approved for the treatment of corticosteroid-refractory BP. However, no treatment option is approved by the Food and Drug Administration for the management of BP. Therefore, developing effective therapies free of debilitating side effects is imperative. In this review, we summarize the main immunologic pathways involved in the pathogenesis of BP, with an emphasis on the role of eosinophils, immunoglobulins, cytokines such as the interleukin (IL)-4 and IL-5, and complements. We further discuss the latest advances with novel therapeutic targets tested for the management of BP. Ongoing efforts are needed to run well-designed controlled trials and test the efficacy and safety of investigational drugs while providing much-needed access to these medications for refractory patients who will not otherwise be able to afford them as off-label prescriptions.

IL-13 Genetic Susceptibility to Bullous Pemphigoid: A Potential Target for Treatment and a Prognostic Marker

Background

Bullous pemphigoid (BP) is a senile chronic autoimmune bullous skin disease with a high relapse rate, which significantly impairs patients’ quality of life and contributes to disease mortality. This observational case-control study explores the gene polymorphisms of cytokines and their clinical significance in Chinese patients with BP.

Methods

IL-1α (rs1800587), IL-1β (rs16944, rs1143627, rs1143634), IL-4 (rs2243250), IL-6 (rs1800795), IL-10 (rs1800896, rs1800871, rs1800872), IL-13 (rs1800925, rs20541), TNF-α (rs1799964, rs1800630, rs1799724, rs361525), IFN-γ (rs1799964, rs1800630, rs361525, rs1800629, rs4248160, rs1800750), and TGF-β1 (rs2317130, rs1800469, rs4803457) genes were genotyped in the healthy controls and BP patients, respectively. Expression of these cytokines in serum was measured. Medical profiles of patients, including baseline characteristics and prognosis, were statistically analyzed.

Results

We found that IL-1 β and IL-13 concentrations were higher in the BP patients’ sera compared to those in the controls. For IL-13, significant differences were found in the nucleotide ratio/genotype/haploid frequency/haplotype, respectively. IL-13 (rs20541, rs1800925) is related to gender, and the IL-13 genotype was significantly associated with recurrence.

Conclusions

BP is associated with IL-13 gene polymorphism and IL-13 concentration is elevated in blood circulation in patients with BP. Our results support that IL-13 is relevant in the pathogenesis of BP, suggesting that IL-13 could potentially represent a promising target for BP therapy and a prognostic marker.

Emerging Biomarkers and Therapeutic Strategies for Refractory Bullous Pemphigoid

Bullous pemphigoid (BP) is the most common autoimmune subepidermal blistering disorder in the elderly. Systemic and topical use of glucocorticoids and immunosuppressants has been shown to be effective in most patients. However, refractory BP patients are challenged to clinicians with severe clinical symptoms, resistance to treatment, and high relapse rate. How to predict and assess the refractory and severity of bullous pemphigoid is the key issue in clinical practice, and the urgent need for precision medicine in refractory patients is driving the search for biomarkers and biologics. Recently, some biomarkers, such as the level of specific autoantibodies and released cytokines, have been proposed as the potential parameters to reflect the disease severity and predict the treatment response and relapse of refractory BP. Moreover, new biologics targeting pathogenic antibodies, complement, Th2 axis, eosinophils, and Th17 axis have shown potent efficacy on refractory BP. Here, we review the literature and give an overview of emerging biomarkers and therapeutic strategies for refractory bullous pemphigoid to improve the prognosis of the patient.

A Review of Acquired Autoimmune Blistering Diseases in Inherited Epidermolysis Bullosa: Implications for the Future of Gene Therapy

Gene therapy serves as a promising therapy in the pipeline for treatment of epidermolysis bullosa (EB). However, with great promise, the risk of autoimmunity must be considered. While EB is a group of inherited blistering disorders caused by mutations in various skin proteins, autoimmune blistering diseases (AIBD) have a similar clinical phenotype and are caused by autoantibodies targeting skin antigens. Often, AIBD and EB have the same protein targeted through antibody or mutation, respectively. Moreover, EB patients are also reported to carry anti-skin antibodies of questionable pathogenicity. It has been speculated that activation of autoimmunity is both a consequence and cause of further skin deterioration in EB due to a state of chronic inflammation. Herein, we review the factors that facilitate the initiation of autoimmune and inflammatory responses to help understand the pathogenesis and therapeutic implications of the overlap between EB and AIBD. These may also help explain whether corrections of highly immunogenic portions of protein through gene therapy confers a greater risk towards developing AIBD.

Tissue eosinophil levels as a marker of disease severity in bullous pemphigoid

BACKGROUND

Eosinophils play an important role in bullous pemphigoid (BP) pathogenesis. Although tissue infiltration with eosinophils has been known for a long time, there is a lack of knowledge about the relationship between tissue eosinophil levels and disease severity and clinical characteristics of the patients.

METHODS

Fifty-nine patients diagnosed with BP between January 2008 and December 2018 were reviewed. Haematoxylin-Eosin (H&E)-stained preparations were re-evaluated in terms of tissue eosinophil levels. For disease severity, Bullous Pemphigoid Disease Area Index (BPDAI) was used. The relationship between tissue eosinophil levels and disease severity and clinical features were evaluated.

RESULTS

Erosion/blister and urticaria/erythema BPDAI scores were higher in the group with high tissue eosinophil level than the group with low tissue eosinophil level. Tissue and peripheral blood eosinophil count were correlated with total urticaria/erythema BPDAI scores. There was no correlation between blood and tissue eosinophil count. The mortality rate was 64.7% vs 44.0% in the high vs low tissue eosinophil groups. Tissue eosinophil levels were high in patients with BP accompanying neurological disease.

CONCLUSIONS

Tissue eosinophil count and peripheral blood eosinophil count were correlated with disease severity in BP. Tissue eosinophil levels were also high in patients with BP accompanying neurological disease.

Association between TH2 Cytokine Gene Polymorphisms and Risk of Bullous Pemphigoid

Background: T-helper 2 (Th2)-associated cytokines are involved in the pathogenesis of bullous pemphigoid (BP), an autoimmune skin disease. Increased expression of Th2 cytokines such as interleukin-4 (IL-4), IL-5, IL-6, IL-10, and IL-13 have been observed in serum, skin biopsies and/or blister fluid. This study aimed to uncover a possible association between Th2 cytokine genetic variations and susceptibility to BP.Methods: In a cohort study, blood samples of BP patients and controls were obtained and variations in IL-4 (rs2243250 and rs2070874), IL-4R (rs1805010), IL-5 (rs2069812), IL-6 (rs1800795), IL-10 (rs1800896, rs1800871, and rs1800872), and IL-13 (rs1800925 and rs20541) were genotyped by PCR-RFLP assays. Furthermore, quantitative expression levels of IL-13 gene were evaluated by real-time RT-PCR analysis.Results: Among the studied variations, a significantly higher frequency of the C-allele was observed in IL-13 gene variation (rs1800925) in the healthy individuals than BP patients. This may indicate a protective effect of C-allele on predisposition to BP. Considering individuals carrying polymorphic genotypes compared to wild genotype, the minor G-allele of IL-4R rs1805010 and A-allele of IL-13 rs20541 had a promotive and protective effect, respectively, on predisposing to the development of BP. No significant difference in IL-13 mRNA expression was detected between BP patients and healthy individuals.Conclusions: Our results indicate that IL-13 rs1800925 variation may be a protective genetic marker for the development of BP. Given this preventive effect against BP, therapeutic strategies could potentially be developed interfering with the functions of IL-13 cytokine, which seems to be integral in the pathogenesis of eosinophilic inflammatory disorders, such as BP.

Eosinophils in Bullous Pemphigoid

Bullous pemphigoid (BP) is an autoimmune blistering disorder with substantial morbidity and mortality. BP is regarded as a disorder driven by IgG due to BP180 and BP230 IgG autoantibodies, yet, new advances highlight the function of eosinophils and IgE autoantibodies in BP. Evidence supports that eosinophils are involved in BP pathogenesis, notably, these include the presence of IL-5, eotaxin, and eosinophil-colony stimulating factor in blister fluid, peripheral blood eosinophilia is present in nearly 50% of affected patients, eosinophils are found against the dermo-epidermal junction (DEJ) when BP serum is present, metalloprotease-9 is secreted by eosinophils at blister sites, blister fluid of BP patients contains eosinophil granule proteins which are located along the lamina lucida of the BMZ in patients with BP and correspond with disease clinically, eosinophil extracellular traps (EET) have been linked to DEJ splitting, IL-5 activated eosinophils cause DEJ separation when BP serum is present, and eosinophils are requisite to drive anti-BP180 IgE mediated blistering of the skin. Yet, the mechanism whereby eosinophils contribute to the pathogenesis of BP remains to be explored. In this review, we examine the role of eosinophils in BP while offering a basis to explain the pathomechanisms of eosinophils in BP.

From bench to bedside: evolving therapeutic targets in autoimmune blistering disease

Autoimmune blistering diseases comprise a group of heterogenous conditions characterized by the loss of tolerance and subsequent development of autoantibodies targeting epidermal and subepidermal adhesion proteins. Blisters and erosions form on the skin and mucous membranes leading to significant morbidity and mortality. Traditional therapies rely on systemic immunosuppression. Advancements in our understanding of the pathophysiology of pemphigus and pemphigoid have led to the development of molecules which target specific pathways involved in induction and perpetuation of disease. In this review, we outline the novel therapeutic strategies including B-cell depletion, T-regulatory cell repletion, cell signalling inhibitors and small molecular inhibitors, inhibitory monoclonal antibodies, as well as complement inhibition. We additionally review their current level of clinical evidence. We lastly review therapeutics targets gleaned from the experimental epidermolysis bullosa acquisita mouse model. These emerging treatments offer an exciting progression from basic science discoveries that have the potential to transform the treatment paradigm in autoimmune blistering diseases.

The Intersection of IgE Autoantibodies and Eosinophilia in the Pathogenesis of Bullous Pemphigoid

Bullous pemphigoid (BP) is an autoimmune blistering disease characterized by autoantibodies targeting cellular adhesion molecules. While IgE autoantibodies are occasionally reported in other autoimmune blistering diseases, BP is unique in that most BP patients develop an IgE autoantibody response. It is not known why BP patients develop self-reactive IgE and the precise role of IgE in BP pathogenesis is not fully understood. However, clinical evidence suggests an association between elevated IgE antibodies and eosinophilia in BP patients. Since eosinophils are multipotent effector cells, capable cytotoxicity and immune modulation, the putative interaction between IgE and eosinophils is a primary focus in current studies aimed at understanding the key components of disease pathogenesis. In this review, we provide an overview of BP pathogenesis, highlighting clinical and experimental evidence supporting central roles for IgE and eosinophils as independent mediators of disease and via their interaction. Additionally, therapeutics targeting IgE, the Th2 axis, or eosinophils are also discussed.

Proteases in Pemphigoid Diseases

Pemphigoid diseases are a subgroup of autoimmune skin diseases characterized by widespread tense blisters. Standard of care typically involves immunosuppressive treatments, which may be insufficient and are often associated with significant adverse events. As such, a deeper understanding of the pathomechanism(s) of pemphigoid diseases is necessary in order to identify improved therapeutic approaches. A major initiator of pemphigoid diseases is the accumulation of autoantibodies against proteins at the dermal-epidermal junction (DEJ), followed by protease activation at the lesion. The contribution of proteases to pemphigoid disease pathogenesis has been investigated using a combination of in vitro and in vivo models. These studies suggest proteolytic degradation of anchoring proteins proximal to the DEJ is crucial for dermal-epidermal separation and blister formation. In addition, proteases can also augment inflammation, expose autoantigenic cryptic epitopes, and/or provoke autoantigen spreading, which are all important in pemphigoid disease pathology. The present review summarizes and critically evaluates the current understanding with respect to the role of proteases in pemphigoid diseases.

Biomarkers related to bullous pemphigoid activity and outcome

Bullous pemphigoid (BP) is the most common autoimmune subepidermal blistering disease of the skin. Investigation of the BP-associated pathophysiological processes during the last decades showed that the generation of autoantibodies directed against the hemidesmosome proteins BP180 and BP230, a hallmark of the BP-associated autoimmune response, leads to the recruitment of inflammatory immune cells at the dermal-epidermal junction, and subsequently to the release of a large amount of inflammatory molecules involved in blister formation. Analysis in transversal and longitudinal studies of autoantibodies and inflammatory molecules production both at the time of diagnosis and under treatment was mainly performed within the serum but also in the blister fluid. Some autoimmune or inflammatory molecules expression was related to the presence of clinical signs, while others were mere bystanders. In this review, we focused on the autoimmune and inflammatory molecules that have been identified as potential biomarkers of BP development and outcome.

Mechanisms of pathogenic effects of eosinophil cationic protein and eosinophil-derived neurotoxin on human keratinocytes

Cutaneous deposition of eosinophil degranulation proteins is a major feature of eosinophil-rich cutaneous diseases including bullous pemphigoid (BP). We sought to better understand the effect of two of these proteins - eosinophil cationic protein (ECP) and eosinophil-derived neurotoxin (EDN), on human keratinocytes using the Het-1A cell line. To evaluate expression of key cytokines and chemokines observed in BP as well as metal metalloprotease 9 (MMP9), we performed qPCR and in-cell Western assays on cells treated with either ECP or EDN. We further evaluated the effect of ECP and EDN on keratinocyte survival, generation of reactive oxygen species (ROS) and apoptosis. Lastly, we assessed ECP and EDN's ability to induce keratinocyte detachment from provisional matrix. Treatment of keratinocytes with ECP and EDN resulted in significant increases in IL-5, eotaxin-1 and CCL5 (RANTES) expression at both mRNA and protein levels, but not IL-17 or IL-31. ECP and EDN also upregulate MMP9 production. Inhibiting MMP9, we confirmed that keratinocyte expression of IL-5, eotaxin-1 and RANTES was independent from MMP9. Both ECP and EDN were cytotoxic to keratinocytes, inducing ROS formation and apoptosis through a mitochondrion-dependent pathway as evidenced by results of terminal deoxynucleotidyl transferase dUTP nick-end labelling (TUNEL) and cytochrome c release assays, respectively. ECP but not EDN led to significant keratinocyte detachment from provisional matrix. These findings demonstrate that the pathogenic effects of ECP and EDN in BP may result from their direct action on keratinocytes, and as such may became a target for future therapies in eosinophil-rich cutaneous diseases.

The Role of Eosinophils in Bullous Pemphigoid: A Developing Model of Eosinophil Pathogenicity in Mucocutaneous Disease

Bullous pemphigoid (BP) is an autoimmune blistering disease which carries a significant mortality and morbidity. While historically BP has been characterized as an IgG driven disease mediated by anti-BP180 and BP230 IgG autoantibodies, developments in recent years have further elucidated the role of eosinophils and IgE autoantibodies. In fact, eosinophil infiltration and eosinophilic spongiosis are prominent features in BP. Several observations support a pathogenic role of eosinophils in BP: IL-5, eotaxin, and eosinophil-colony stimulating factor are present in blister fluid; eosinophils line the dermo-epidermal junction (DEJ) in the presence of BP serum, metalloprotease-9 is released by eosinophils at the site of blisters; eosinophil degranulation proteins are found on the affected basement membrane zone as well as in serum corresponding with clinical disease; eosinophil extracellular DNA traps directed against the basement membrane zone are present, IL-5 activated eosinophils cause separation of the DEJ in the presence of BP serum; and eosinophils are the necessary cell required to drive anti-BP180 IgE mediated skin blistering. Still, it is likely that eosinophils contribute to the pathogenesis of BP in numerous other ways that have yet to be explored based on the known biology of eosinophils. We herein will review the role of eosinophils in BP and provide a framework for understanding eosinophil pathogenic mechanisms in mucocutaneous disease.

Eosinophils as putative therapeutic targets in bullous pemphigoid

Bullous pemphigoid (BP) is the most common autoimmune subepidermal blistering skin disease and is characterized by the presence of autoantibodies directed against the hemidesmosomal proteins BP180 and BP230 that can be detected in the skin and serum of BP patients. Histologically, the dermal infiltration of eosinophils is obvious. The objective of this review was to present evidence that eosinophils play a key role in the pathogenesis of BP. Eosinophils, together with cytokines and chemokines regulating their production, recruitment and activation, are abundantly present in lesional skin, in blisters and in peripheral blood of patients with BP. Recently, using a cryosection model, eosinophils were demonstrated to induce dermal-epidermal separation in the presence of BP antibodies. Thus, eosinophils and their products, as well as mediators regulating their function, present promising targets for the treatment of BP.

Expression of the JAK/STAT Signaling Pathway in Bullous Pemphigoid and Dermatitis Herpetiformis

A family of eleven proteins comprises the Janus kinases (JAK) and signal transducers and activators of transcription (STAT) signaling pathway, which enables transduction of signal from cytokine receptor to the nucleus and activation of transcription of target genes. Irregular functioning of the cascade may contribute to pathogenesis of autoimmune diseases; however, there are no reports concerning autoimmune bullous diseases yet to be published. The aim of this study was to evaluate the expression of proteins constituting the JAK/STAT signaling pathway in skin lesions and perilesional area in dermatitis herpetiformis (DH) and bullous pemphigoid (BP), as well as in the control group. Skin biopsies were collected from 21 DH patients, from 20 BP patients, and from 10 healthy volunteers. The localization and expression of selected STAT and JAK proteins were examined by immunohistochemistry and immunoblotting. We found significantly higher expression of JAK/STAT proteins in skin lesions in patients with BP and DH, in comparison to perilesional skin and the control group, which may be related to proinflammatory cytokine network and induction of inflammatory infiltrate in tissues. Our findings suggest that differences in the JAK and STAT expression may be related to distinct cytokines activating them and mediating neutrophilic and/or eosinophilic infiltrate.

Analysis of serum markers of cellular immune activation in patients with bullous pemphigoid

Experimental models of bullous pemphigoid (BP), the most frequent subepidermal autoimmune bullous disease, revealed that the immune response leading to blister formation represents an incompletely understood complex process involving different inflammatory cells. In contrast to previous reports commonly focusing on limited molecular and cellular phenotypes of the disease, the aim of this study was to investigate a broad spectrum of markers of cellular immune activation in patients with BP. We found that serum levels of soluble CD4, myeloperoxidase, S100A12, eosinophil cationic protein and soluble P-selectin were significantly elevated in patients with active BP compared with normal controls. Mast cell tryptase and neopterin serum levels significantly decreased at the time of clinical remission of the patients. Additionally, serum concentrations of soluble IL-2 receptor, mast cell tryptase and soluble P-selectin were significantly associated with levels of circulating anti-BP180 autoantibodies. Our findings confirm and extend previous reports suggesting some concomitant involvement of a panel of molecules representative for a wide spectrum of cellular players (T cells, mast cells, neutrophils, eosinophils, macrophages and platelets) orchestrating the inflammatory reaction in BP. These data may favour the employment of broad-spectrum or combined immunosuppressants, potentially together with an anticoagulant treatment, over cell- or molecule-specific targeted therapy in patients with this disorder.

Eosinophil Cationic Protein (ECP), a predictive marker of bullous pemphigoid severity and outcome

Bullous Pemphigoid (BP) is an inflammatory rare autoimmune bullous dermatosis, which outcome cannot be predicted through clinical investigations. Eosinophils are the main immune infiltrated cells in BP. However, the release of Major Basic Protein (MBP), Eosinophil Derived Neurotoxin (EDN), and Eosinophil Cationic Protein (ECP) upon eosinophil activation has still not been evaluated with respect to BP development. MBP, EDN and ECP were measured by ELISA in serum (n = 61) and blister fluid (n = 20) of patients with BP at baseline, and in serum after 2 months of treatment (n = 41). Eosinophil activation in BP patients was illustrated at baseline by significantly higher MBP, EDN and ECP serum concentrations as compared with control subjects (n = 20), but without distinction according to disease severity or outcome. EDN and ECP values were even higher in the blister fluids (P < 0.01 and P < 0.05, respectively), whereas MBP values were lower (P < 0.001). ECP serum concentration decreased after 60 days of treatment in BP patients with ongoing remission but not in patients who later relapsed (P < 0.05). A reduction of at least 12.8 ng/mL in ECP concentrations provided a positive predictive value for remission of 81%, showing that ECP serum variation could be a useful biomarker stratifying BP patients at risk of relapse.

Eosinophils in Autoimmune Diseases

Eosinophils are multifunctional granulocytes that contribute to initiation and modulation of inflammation. Their role in asthma and parasitic infections has long been recognized. Growing evidence now reveals a role for eosinophils in autoimmune diseases. In this review, we summarize the function of eosinophils in inflammatory bowel diseases, neuromyelitis optica, bullous pemphigoid, autoimmune myocarditis, primary biliary cirrhosis, eosinophilic granulomatosis with polyangiitis, and other autoimmune diseases. Clinical studies, eosinophil-targeted therapies, and experimental models have contributed to our understanding of the regulation and function of eosinophils in these diseases. By examining the role of eosinophils in autoimmune diseases of different organs, we can identify common pathogenic mechanisms. These include degranulation of cytotoxic granule proteins, induction of antibody-dependent cell-mediated cytotoxicity, release of proteases degrading extracellular matrix, immune modulation through cytokines, antigen presentation, and prothrombotic functions. The association of eosinophilic diseases with autoimmune diseases is also examined, showing a possible increase in autoimmune diseases in patients with eosinophilic esophagitis, hypereosinophilic syndrome, and non-allergic asthma. Finally, we summarize key future research needs.

IgE-mediated mechanisms in bullous pemphigoid and other autoimmune bullous diseases

Autoimmune bullous diseases (AIBDs) are characterized by autoantibodies against structural proteins of the dermal-epidermal junction (in pemphigoid diseases) and the epidermal/ epithelial desmosomes (in pemphigus diseases). By far, the most common AIBD is bullous pemphigoid, which is immunopathologically characterized by autoantibodies against BP180 (type XVII collagen) and BP230. IgG and, to a lesser extent, IgA autoantibodies are the major autoantibody isotypes in these disorders. IgE autoantibodies are increasingly reported in particular in bullous pemphigoid. The development of specific and sensitive anti-BP180 IgE ELISA systems, the report of two experimental murine models employing IgE autoantibodies against BP180, and the successful treatment of bullous pemphigoid with the anti-IgE antibody omalizumab have raised interest in the role of IgE autoantibodies and the modulation of their production in AIBDs. Here, the relevance of IgE autoantibodies in the diagnosis, pathophysiology, and treatment decisions of AIBDs, with a focus on bullous pemphigoid, is reviewed.

Eosinophil localization to the basement membrane zone is autoantibody- and complement-dependent in a human cryosection model of bullous pemphigoid

Bullous pemphigoid (BP) is an autoimmune blistering disease characterized by antibodies (IgG and IgE) targeting cell-substrate adhesion proteins. A variety of BP models suggest that autoantibody-dependent neutrophil degranulation is essential for blister formation. However, lesional biopsies reveal a predominance of eosinophils and few neutrophils. Our goal was to evaluate the role of antibodies and complement in eosinophil localization, degranulation and split formation at the dermo-epidermal junction (DEJ) utilizing a human skin cryosection model of BP paired with a human eosinophilic cell line, 15HL-60. Expression of receptors for IgG (FcγRII), IgE (FcεRI) and complement (CR1 and CR3) was confirmed on 15HL-60 cells using flow cytometry. 15HL-60 expression of granule protein [eosinophil derived neurotoxin (EDN) and eosinophil peroxidase (EPO)] mRNA and their degranulation in vitro was confirmed using RT-PCR and ELISA, respectively. For cryosection experiments, BP or control sera or IgG and IgE antibodies purified from BP sera were utilized in combination with 15HL-60 cells ± fresh complement. Both BP serum and fresh complement were required for localization of 15-HL60 cells to the DEJ. Interestingly, eosinophil localization to the DEJ was dependent on IgG, but not IgE, and complement. However, no subepidermal split was observed. Additionally, the 15HL-60 cells did not degranulate under any experimental conditions and direct application of cell lysate to cryosections did not result in a split. Our observation that eosinophil localization to the DEJ is dependent on IgG mediated complement fixation provides additional insight into the sequence of events during the development of BP lesions.

IgE autoantibodies in bullous pemphigoid: supporting role, or leading player?

Bullous pemphigoid (BP) is a common autoimmune blistering skin disease in which two hemidesmosomal components--the transmembrane collagen XVII (BP180 or BPAG2) and the plakin family protein BP230 (BPAG1)--are targeted by autoimmunity. Of these, collagen XVII (COL17) is thought to be a major autoantigen, and vital roles of IgG autoantibodies in blister formation have been elucidated. However, BP shows distinct features, including pruritic urticarial erythema and eosinophilic infiltration, which may be independent of IgG-mediated autoimmunity. Recently, it has been revealed that sera from certain patients with BP contain IgE autoantibodies to COL17 and that IgE autoantibodies bind to peri-lesional dermal-epidermal junctions. Mouse models have demonstrated that IgE antibodies to COL17 induce erythema and eosinophilic infiltration in skin. In addition, the successful treatment of severe BP with omalizumab, a humanized monoclonal antibody targeting IgE, has been reported. These findings suggest that both IgG and IgE autoantibodies to COL17 may be involved in the BP pathogenesis. This article summarizes IgE-mediated autoimmunity to COL17 in BP.

Increased risk of stroke in patients with bullous pemphigoid: a population-based follow-up study

BACKGROUND AND PURPOSE

Although previous research reveals that cardiovascular events and thromboembolic diseases are important causes of death in patients with bullous pemphigoid (BP), the risk of stroke after the diagnosis of BP relative to the general population remains unknown. Using a randomly selected nationwide population-based sample, this study investigates the risk of stroke in patients with BP compared with unaffected individuals of a similar age.

METHODS

This study analyzes data from Taiwan's National Health Insurance Research Database. This sample included 390 patients with BP and 1950 matched subjects as a comparison group. Stratified Cox proportional hazard regressions were used to calculate the 3-year stroke risk for these 2 groups after adjusting for patient's age, sex, and comorbid medical disorders at baseline.

RESULTS

Of the 2340 patients in the sample, 312 patients (13.3%) had strokes during the 3-year follow-up period, 89 (22.8% of the patients with BP) in the study group and 223 (11.4% of patients without BP) in the comparison group (P<0.001). The hazard ratio for stroke for patients with BP was 2.37 (95% CI, 1.78 to 3.15; P<0.001) times as high that for patients without BP within the 3-year follow-up period after adjusting for hypertension, diabetes, hyperlipidemia, heart failure, atrial fibrillation, and coronary heart disease.

CONCLUSIONS

Patients with BP have an increased risk of stroke and particularly ischemic stroke.

The pathophysiology of bullous pemphigoid

Bullous pemphigoid (BP) is a blistering skin disease characterized by an autoimmune response to 2 hemidesmosomal proteins within the dermal-epidermal junction, designated BP180 and BP230. While BP230 localizes intracellularly and associates with the hemidesmosomal plaque, BP180 is a transmembrane glycoprotein with an extracellular domain. Most BP patients have autoantibodies binding to an immunodominant region of BP180, the noncollagenous 16A domain (NC16A), which is located extracellularly close to the transmembrane domain of the protein. Autoreactive T and B cell responses to BP180 have been found in patients with BP. Passive transfer of antibodies to the murine BP180 ectodomain triggers a blistering skin disease in mice that closely mimics human BP. Lesion formation in this animal model depends upon complement activation, mast cell degranulation and accumulation of neutrophils and eosinophils. Patients' autoantibodies to BP180 induce dermal-epidermal separation in cryosections of human skin when co-incubated with leukocytes. The loss of cell-matrix adhesion is mediated by proteinases released by granulocytes. The increased knowledge of the pathophysiology of BP should facilitate the development of novel therapeutic strategies for this disease.

Oral steroid improves bullous pemphigoid-like clinical manifestations in non-Herlitz junctional epidermolysis bullosa with COL17A1 mutation

Non-Herlitz junctional epidermolysis bullosa (JEB-nH), a nonlethal variant of junctional epidermolysis bullosa (JEB), is an autosomal recessive disorder characterized by separation of the dermal-epidermal junction. JEB-nH is caused by mutations in several genes and lack of the COL17A1 gene product may lead to skin fragility. A 41-year-old Japanese man with JEB-nH, featuring mutations in the gene encoding type XVII collagen, presented with great blisters over his entire body accompanied by severe itching and eosinophilia usually observed in bullous pemphigoid (BP). To our knowledge, our patient is the first with JEB-nH to be treated successfully with an oral steroid to control his skin affliction, symptoms and eosinophilia. This suggests that in the case of JEB-nH with eosinophilia caused by some secondary immune activation, oral steroids may constitute an alternate therapy to improve aggravated skin conditions and severe itching, both of which tend to show resistance to usual dermatological treatments.

Serum chemokine profile in patients with bullous pemphigoid

BACKGROUND

Bullous pemphigoid (BP) is an autoimmune inflammatory disease causing blister formation at the dermoepidermal junction. Cutaneous infiltration of activated CD4+ T cells and eosinophils is an early event in blister formation during the disease process, suggesting that the trafficking of circulating leucocytes through the sites of inflammation is crucial in the pathogenesis of the disease. While the accumulated evidence suggests that some cytokines are involved in the pathogenesis, there have been few reports about serum chemokine profiles in patients with BP.

OBJECTIVES

To determine serum profiles of various chemokines and their clinical association in patients with BP.

METHODS

Concentrations of 10 chemokines - interferon (IFN)-gamma-inducible protein-10 (IP-10), monokine induced by IFN-gamma (MIG), macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, RANTES, eotaxin, monocyte chemoattractant protein (MCP)-1, MCP-2, MCP-3 and growth-regulated oncogene-alpha- were measured in serum samples from 38 patients with BP, 16 with pemphigus vulgaris (PV) and 17 normal controls using a sandwich immunoassay-based multiplex protein array system.

RESULTS

While there was no significant increase in any serum chemokine levels in patients with PV, serum levels of IP-10 and MCP-1 were significantly increased in patients with BP compared with healthy controls. Furthermore, serum levels of IP-10, MIG, MCP-1 and eotaxin in patients with BP increased significantly with disease severity as determined by the area affected.

CONCLUSIONS

These observations suggest that an elaborately orchestrated network of chemokines, especially MCP-1 and IP-10, contributes to the pathomechanism of BP.

Tissue Eosinophilia in Pemphigoid Gestationis: Association with Eotaxin and Upregulated Activation Markers on Transmigrated Eosinophils

PROBLEM

We studied chemotactic cytokines and activation of skin-homed eosinophils in pemphigoid gestationis, a rare autoimmune bullous disease of late pregnancy.

METHOD OF STUDY

Eotaxin and interleukin (IL)-5 were analysed in patients' blister fluid and serum by enzyme-linked immunosorbent assay. Lesional tissue was investigated for eotaxin deposition by immunohistochemistry. Adhesion molecules and activation markers on tissue eosinophils were analysed by immunofluorescence staining.

RESULTS

Eotaxin was elevated in serum of two pemphigoid gestationis patients compared with nine healthy pregnant women. Blister fluid contained even higher amounts of eotaxin and in addition IL-5. Eotaxin was mainly expressed in subepidermal tissue in close proximity to eosinophils that expressed high levels of adhesion molecules (CD11b, CD11c, CD18 and CD49d) and the activation marker HLA-DR.

CONCLUSIONS

High local levels of eotaxin and IL-5 as present in the blister fluid correspond to the high state of activation of the infiltrated eosinophils.

High levels of interleukin-1 in patients with endemic pemphigus foliaceus

Endemic pemphigus foliaceus (EPF) is an autoimmune disease characterized by blister formation with a loss of cohesion and infiltration of inflammatory cells. We observed that supernatants of peripheral blood mononuclear cells from patients produced significantly more interleukin-1beta (IL-1beta) than those from stimulated healthy controls. Furthermore, a Th2 bias was observed in EPF patients when the IL-5/gamma interferon ratio was analyzed. These results indicate that cells from pemphigus patients react with a vigorous proinflammatory response.

Successful treatment by double-filtration plasmapheresis of a patient with bullous pemphigoid: effects in vivo on transcripts of several genes for chemokines and cytokines in peripheral blood mononuclear cells

The involvement of various cytokines and chemokines has been reported in the pathogenesis of bullous pemphigoid (BP). Double-filtration plasmapheresis (DFPP) is an effective treatment for BP but the mechanism of action remains unclear. Using semiquantitative reverse transcription-polymerase chain reaction, we examined levels of transcripts for various cytokines and chemokines in freshly isolated peripheral blood mononuclear cells in a patient with BP before and after DFPP treatment. DFPP was performed four times. Relative levels of transcripts for interleukin (IL)-8, macrophage inflammatory protein (MIP)-1alpha and IL-5, and the ratio of relative levels of transcripts for IL-4 and interferon (IFN)-gamma, were higher, before treatment, than in healthy controls, and decreased when the extent of the lesions was reduced. Relative levels of transcripts for tumour necrosis factor (TNF)-alpha and IL-4 also decreased with regression of lesions, although they were similar to or lower than the corresponding levels in healthy individuals. When eruptions recurred, relative levels of transcripts for IL-8, MIP-1alpha, RANTES (regulated upon activation normal T cell expressed and secreted), IL-2, IFN-gamma and TNF-alpha were very much higher than those prior to the recurrence, while relative levels of mRNAs for IL-4 and IL-5 did not increase. Relative levels of transcripts for IL-8, MIP-1alpha, TNF-alpha and IL-2 were lower at the end of each individual DFPP and after the four treatments than at the beginning of treatment. Our observations suggest that cytokines and chemokines produced in mononuclear cells play important roles in the pathogenesis of BP and that regulation of their expression might be involved in the therapeutic effects of DFPP in BP.

Serum eosinophil cationic protein, myeloperoxidase, tryptase, eotaxin and Th2-L-like cytokines in Dermatitis herpetiformis

BACKGROUND

Dermatitis herpetiformis (DH) is a subepidermal bullous disease characterized by a neutrophilic and eosinophilic infiltrate, together with activated lymphocytes that show preferential polarization towards the Th2-like phenotype. To date, the role of neither soluble mediators, such as cytokines, nor serum levels of myeloperoxidase (MPO), eosinophil cationic protein (ECP) and tryptase (TRY) have been studied in the peripheral blood of DH. In this study we investigated 40 DH subjects for possible alterations in MPO, ECP, TRY, eotaxin, interleukin (IL) 4 and IL-5 concentrations to evaluate the role of neutrophils, eosinophils and mast cells in the induction of skin lesions. Sera from 20 healthy subjects were tested as controls.

METHODS

Eotaxin, IL-4 and IL-5 serum contents were determined by a solid-phase enzyme-linked immunosorbent assay. A double antibody radioimmunoassay was used to measure serum levels of MPO, ECP and TRY.

RESULTS

Normal levels of eotaxin and IL-4 were found in all DH subjects; increased IL-5 levels were found only in 1 subject. The MPO levels were significantly higher in DH subjects than in healthy controls (p < 0.01). There was also a significant difference between the serum ECP levels of DH and healthy controls (p < 0.05). TRY was not revealed in the serum of DH subjects.

CONCLUSIONS

The determination of Th2-like cytokines and TRY serum levels is not important in quantifying the involvement of activated lymphocytes and mast cells in DH; however, the finding of high MPO and ECP serum levels seems to confirm that these products are good markers of the presence of activated neutrophils and eosinophils.

Immunologic and histopathologic characterization of an active disease mouse model for pemphigus vulgaris

Pemphigus vulgaris is an autoimmune blistering disease of the skin and mucous membranes that is caused by anti-desmoglein 3 IgG autoantibodies. Recently, we generated an active disease mouse model for pemphigus vulgaris by adoptive transfer of splenocytes from immunized desmoglein 3-/- mice to Rag2-/- mice. In this study, we performed immunologic and histopathologic studies using this pemphigus vulgaris model in mice and compared the gross and microscopic phenotypes of pemphigus vulgaris model mice and desmoglein 3-/- mice. Pemphigus vulgaris model mice showed strong in vivo IgG, and weak IgA deposition on keratinocyte cell surfaces in stratified squamous epithelia, and produced circulating anti-desmoglein 3 IgG antibodies without apparent cross-reactivity to desmoglein 1, in enzyme-linked immunosorbent assays. The predominant IgG subclass was IgG1. Pemphigus vulgaris model mice and desmoglein 3-/- mice were almost indistinguishable in terms of both gross and microscopic findings. Both types of mice showed suprabasilar acantholysis in the stratified squamous epithelia, including the oral mucous membranes and traumatized skin around the snout or paws; however, some pemphigus vulgaris model mice demonstrated a more severe phenotype than desmoglein 3-/- mice. The esophagus and forestomach were affected in some pemphigus vulgaris model mice, but not in desmoglein 3-/- mice. Furthermore, eosinophilic spongiosis, which is found in early pemphigus vulgaris lesions in patients, was observed in pemphigus vulgaris model mice but not in desmoglein 3-/- mice. Pemphigus vulgaris model mice reflect several of the histopathologic and immunologic features seen in pemphigus vulgaris patients, and provide a valuable tool to investigate the pathophysiologic mechanisms of pemphigus vulgaris.

Skin-homing interleukin-4 and -13-producing cells contribute to bullous pemphigoid: remission of disease is associated with increased frequency of interleukin-10-producing cells

Although evidence is accumulating that type 2 cytokines play a part in the pathogenesis of bullous pemphigoid, little information is available concerning characterization of the cellular source of these cytokines involved in the pathogenesis of bullous pemphigoid. By using multiparameter flow cytometry, we investigated T cells capable of producing interleukin-2, -4, -10, and -13, interferon-gamma, and tumor necrosis factor-alpha and their correlated expression of skin-homing receptor (cutaneous lymphocyte-associated antigen) in peripheral blood and skin blister of patients with bullous pemphigoid. In peripheral blood of bullous pemphigoid patients, significantly increased frequencies of interleukin-4- and interleukin-13-producing cells were found as compared with those of healthy controls, and the majority of these type 2 cells was found in the cutaneous lymphocyte-associated antigen-positive population. The frequency of interferon-gamma-producing cells was also increased as compared with healthy subjects; however, the majority of this subset was found in the cutaneous lymphocyte-associated antigen-negative population. In the skin blister, the frequencies of interleukin-13- and interleukin-4-producing cells were much higher than those in the peripheral blood of bullous pemphigoid, whereas that of interferon-gamma producing cells was significantly lower. Furthermore, in bullous pemphigoid patients after therapy with systemic corticosteroids, the frequency of cutaneous lymphocyte-associated antigen-positive, but not cutaneous lymphocyte-associated antigen-negative, interleukin-13-producing cells was significantly decreased accompanied by an increased frequency of interleukin-10-producing cells, which was associated with clinical improvement. Thus, our results suggest that bullous pemphigoid is a unique organ-specific autoimmune disease characterized by an expansion of skin-homing interleukin-13-producing cells. In addition, corticosteroids may control such type 2 biased inflammatory responses in bullous pemphigoid by promoting the expansion of interleukin-10-producing cells.

Genotypic and phenotypic characterization of Staphylococcus aureus strains isolated in subjects with atopic dermatitis. Higher prevalence of exfoliative B toxin production in lesional strains and correlation between the markers of disease intensity and colonization density

Staphylococcus aureus strains generally colonize eczematous lesions of subjects with atopic dermatitis much more frequently than in the skin of normal individuals. The aim of this study was to provide a detailed genotypic and phenotypic analysis of S. aureus strains colonizing four different sites (lesional and non-lesional skin areas, nasal and pharyngeal mucosas) of 49 patients with atopic dermatitis. The 88 isolates were analyzed in duplicate by pulsed field gel electrophoresis and in their exfoliative toxin A or B production by latex test. The patients were characterized by age, sex, severity scoring of atopic dermatitis and serum eosinophil cationic protein. Fourteen (28.6%) of the patients were completely negative for S. aureus while 35 (71.4%) were positive in at least one site. The severity scores and eosinophil cationic protein levels were significantly correlated variables (P<0.001), linked to the colonization intensity (P ranging between 0.05 and <0.001 depending on the site) and to the number of colonized sites (P at least <0.01). The genotypic patterns, widely heterogeneous, showed no restriction to peculiar patterns. Only eight strains produced exfoliative toxin B which was significantly restricted to the lesional isolates (P=0.012).

Characterization of the CC chemokine receptor 3 on human keratinocytes

CC chemokine receptors are expressed on hematopoietic cells, and these may impart selective homing of monocyte, leukocyte, and lymphocyte subsets to sites of inflammation. CC chemokine receptor 3 is the major receptor on eosinophils and is also expressed on other inflammatory cells suggesting its important role for allergic diseases such as atopic dermatitis and bronchial asthma. Eotaxin, eotaxin-2 and eotaxin-3 have been identified as ligands that only activate CC chemokine receptor 3. CC chemokine receptor 3 is also activated by other promiscuous ligands, however, such as RANTES and monocyte chemotactic protein 4. To date, CC chemokine receptor 3 has not been reported to be expressed on nonhematopoietic cells. In this study, we investigated whether keratinocytes possess autocrine and paracrine mechanisms for CC chemokine secretion and receptor expression as reported for the expression of interleukin 8 and its receptors. Reverse transcriptase polymerase chain reaction analysis demonstrated that CC chemokine receptor 3 mRNA is expressed constitutively in cultured keratinocytes. The signal quantities of the CC chemokine receptor 3 amplicons showed lower intensities for keratinocytes than for eosinophils. In situ hybridization techniques exhibited that basal cell layers of the epidermis were stained homogeneously for CC chemokine receptor 3 mRNA with a decreasing signal to the upper epidermis showing that differentiating and proliferating keratinocytes did express mRNA specific for CC chemokine receptor 3. Immunohistochemical studies confirmed low expression of CC chemokine receptor 3 protein on epidermal keratinocytes compared to the high level observed on infiltrating eosinophils. Furthermore, stimulation of cultured keratinocytes with eotaxin resulted in an increased [3H]thymidine incorporation indicating a role of CC chemokine receptor 3 in epidermal proliferation and differentiation. These data demonstrate that CC chemokine receptor 3 is expressed not only on hematopoietic cells but also on keratinocytes as nonhematopoietic cells with ectodermal origin. Therefore, the identification of CC chemokine receptor 3 on epidermal keratinocytes may indicate a role for CC chemokine receptor 3 and its ligands in skin physiology and pathophysiology.

Bullous pemphigoid: interaction of interleukin 5, anti-basement membrane zone antibodies and eosinophils. A preliminary observation

Bullous pemphigoid (BP) is an autoimmune blistering skin disease characterized by the presence of autoantibodies to normal components of the hemidesmosome (BPAg1 and BPAg2). Histology of skin lesions demonstrate a subepidermal vesicle and a predominantly eosinophilic dermal cellular infiltrate. Interleukin 5 (IL-5) plays a major role in eosinophil recruitment and function. Using an ELISA, we investigated the levels of IL-5 in the sera and blister fluid of BP patients with active disease and those in prolonged clinical remission treated with intravenous immunoglobulin, and compared it to that in normal controls. Significantly increased levels of IL-5 were detected in the serum and particularly the blister fluid of patients with active disease (P=0.0043) when compared to levels in normal controls. There was no significant difference in IL-5 levels in patients in prolonged clinical remission compared to normal control serum. In an immunoblot assay, using bovine gingival lysate as substrate, we determined the presence of IgG and IgE autoantibodies specific to basement membrane zone proteins in blister fluid and serum of BP patients. IgG autoantibodies to BPAg1 and BPAg2 were detected in both blister fluid and serum of patients, whereas IgE autoantibodies, in much lower titers, were detected to only BPAg1. Elevated levels of blood and tissue eosinophilia were observed in these patients. Based on these data, we present a preliminary hypothesis for the initiation, progression and localization of blister formation in BP.

Elevated levels of eotaxin and interleukin-5 in blister fluid of bullous pemphigoid: correlation with tissue eosinophilia

BACKGROUND

Bullous pemphigoid (BP) often provokes blood and tissue eosinophilia, which suggests that some chemoattractants modulate the eosinophil infiltration in BP. Eotaxin, a CC chemokine, strongly attracts eosinophils, and interleukin (IL)-5 induces eosinophil differentiation, proliferation and colony formation in vitro.

OBJECTIVES

To examine the correlation between levels of eotaxin and IL-5 and the number of lesional eosinophils, and the expression of eotaxin in BP lesions.

PATIENTS/METHODS

In this study we measured eotaxin and IL-5 levels in blister fluid of BP by enzyme-linked immunosorbent assay. We also examined the expression of eotaxin in BP lesions by immunohistochemistry.

RESULTS

Both eotaxin and IL-5 were detected at high levels in BP blister fluid. Blister fluid eotaxin, but not IL-5 levels, correlated significantly with the number of dermal infiltrating eosinophils. By immunohistochemistry, eotaxin was strongly expressed in epidermal keratinocytes around BP blisters.

CONCLUSIONS

These findings suggest that eotaxin and IL-5 are strongly associated with the tissue eosinophilia of BP. Therapies which aim to inhibit production of eotaxin and IL-5 may improve the inflammation and blister formation in BP.